This invention relates to a method for making the heat transfer surfaces of cooling water systems and boilers resistant to the formation of scale deposits and fouling. More particularly the invention is a method for making heat transfer surfaces resistant to the deposition of scale and fouling by coating the surfaces with a film of plasma-polymerized fluoroethylene monomer.
In heat exchange equipment, the formation of scale and fouling on heat transfer surfaces lowers the efficiency of the surface and can cause overheating and damage. Scaling is caused by crystallization and/or precipitation of salts, mainly calcium carbonate, to form a hard adherent layer on the surface. Such scale may be controlled by pretreatment to remove scale-forming constituents or by increasing or broadening the solubility of scale-forming salts through use of dispersants, often coupled with blowdown procedures to remove accumulated sludges and to lower the concentration of dissolved solids. Although many such prior art methods exist which markedly reduce the scaling rate, these do not completely eliminate the problem and with time, scaling becomes sufficient to reduce efficiency and requires cleaning and/or replacement of the heat transfer surfaces. A method for reducing the formation of adherent scale on heat transfer surfaces could alone be a useful advance in the art, and could when used with prior art water treatment processes markedly extend the useful life of heat transfer equipment.